Rotary compressor



Aug. 21, 1928. 1,681,574 c. c. FARMER I ROTARY COMPRES SOR Filed March1, 1923 INVENTOR CLYDE C. FARMER ATTORNEY I Patented Aug. 21, 1928.

UNITED STATES PATENT OFFICE.

CLYDE C. FARMER, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOB TO THE WESTING-HOUSE AIR BRAKE COMPANY, OF WILLIERDING, PENNSYLVANIA, A CORPORA- TIONOF PENNSYLVANIA.

ROTARY COMPRESSOR.

Application filed March 1, 1923. Serial No. 622,099.

This invention relates to rotary compressors and the principal object ofmy invention is to provide means for cooling and lubricating a rotarycompressor.

In the accompanying drawing; Fig. 1 1s a diagrammatic view, partly insectlon of a lubricating and cooling system applied to a rotarycompressor in accordance with my invention; and Fig. 2 a plan view,partly in section, of the rotary compressor shown in Fig. 1.

The rotary compressor may comprise a casing 1 having a cylindricalchamber 2 within which is 'eccentrically mounted a rotor shaft 3. On theshaft 3 is mounted a rotor member 4 having radialslots 5 for receivingradially movable rotor blades 6.

The rotor rotates in the direction of the arrow. as shown in Fig. 1 andthe air inlet 7 is connected by pipe 8 to a suitable suction inlet airstrainer 9. The outlet 10 for compressed air is connected by pipe 11 toan oil reservoir 12 which is charged with a suitable quantity oflubricating oil 13.

From the oil reservoir 12, compressed air passes through a suitable oilseparator 14, adapted to separate oil from the compressed air, to a pipe15 which is connected to a compressed air storage reservoir 16.

' The rotary compressor is provided with an annular chamber 17 throughwhich water circulates for the purpose of cooling the compressor and thecirculating water is .cooled by means of a radiator 18, preferably ofthe Well known automotive type.

Immersed in the lubricating oil 13 in the reservoir 12 is a thermostat19 which is operatively connected by'a lever 20 to a shaft 21 carrying alever 22. Associated with the reservoir 12 is a'valve casing 23containing a valve 24 for controlling the flow of cooled water from theradiator 18'through pipe 25 to a pipe 26 which is connected to chamber17 of the rotary compressor. A valve stem 27 is connected to valve 24and extends out of casing 23 in position to be engaged by the end oflever 22. Cooling water flowing through pipe 26 to chamber .17 flowsback to the radiator 18 by way of pipe 28.

Lubricating oil from reservoir 12, under the pressure of the compressedair in said reservoir, flows through pipe 29 into the rotor bearingchamber 30 of the rotary compressor. A hole 31 is drilled through theaxis of the rotor shaft 3 and from this hole, radial ports 32 lead tothe" respective rotor blade slots 5.

In order to prevent possible leakage of oil at the rotor shaft bearingto thedriving electric motor 33, an annular chamber 34 is providedbetween the compressor and the motor and surrounding the shaft bearing.Said chamber is connected by a passage 35 to a pipe 36 leading to thecompressor air inlet pipe 8, so that any oil leaking into the chamber 34will be returned to the compressor by the suction or partial vacuumexisting in the inlet pipe 8.

In operation, when the rotary compressor is started, the temperature ofthe oil 13 in the reservoir 12 will be relatively low and the thermostatrod 19 will therefore be retracted so that the lever 22 will be in theposition shown in Fig. 1, permitting the valve-24 to seat. WVith thevalve 24 seated there is no circulation of cooling water through therotary compressor. As thecompressor operates air is compressed by thewell known action of the blades 6 and the compressed air passes throughpipe 11 to the oil reservoir 12. The pressure of air thus created inreservoir 12 causes a flow of lubricating oil from reservoir 12 throughpipe 29 to the rotary compressor and the oil then flows through the hole31 and the radialports 32, so as to lubricate the compressor and any oilflowing past the rotor shaft bearing will be trapped in chamber 34,whence it will be drawn through pipe36 by the suction in pipe 8 to theinlet opening 7 of the compressor.

The act of compressing air heats the same and tends to heat. thecompressor and the heated compressed air flowing into the oil reservoir12 heats the oil 13 therein.

When the temperature of the oil has risen to a predetermined degree, thethermostat will act by expansion to raise the lever 22 so as to lift thevalve 24 fromits seat. Cooling water is then permitted to circulatethrough the compressor, as supplied from the radiator 18, and this tendsto cool the compressor and also reduce the temperature of the compressedair. If the temperature of the compressed air should fall below a-predetermined degree, the thermostat will operate to permit the valve24 to close or partially 'close so as o cut off or reduce the flow ofable that this water should not condense and mingle with the oil supplyin the reservoir 12 and therefore the thermostatic control mechanism isso adjusted that the temperature of the compressed air will bemaintained high enough to maintain the water in a vaporized form, sothat it will be held in suspension in the compressed air and will passout of the oil reservoir 12 without condensation and be carried overinto the air storage reservoir 16.

On the other hand, the temperature of the lubricating oil should not beallowed to rise to a point at which the oil will vaporize and thus passout with the water vapor to the storage reservoir, or at which it isliable to burn, or at which its lubricating qualities are reduced, andconsequently the thermostatic control mechanism is so adjusted that thetemperature of the oil will not be increased above a predetermineddegree. I

The thermostatic control is thus made to work between two range limits,the higher limit to prevent the oil from becoming heated to such anextent as to permit vaporization of the oil, and the lower limit toprevent the cooling of the compressed air to such anextent that watercarried with the air will tend to condense in the oil reservoir The oilcarried by the compressed air into the reservoir 12 being in the form ofminute particles carried in suspension and not in a gaseous form, theoil separator readily operates in the well known manner to separate theoil from the air and allow same to flow back into the oil reservoir.

Having now described my invention, what I claim as new and desire tosecure by Let-' ters Patent, is

1. The combination with a rotary fluid compressor, of a reservoir intowhich flows fluid compressed by the compressor and containing a quantityof oil, means for supplymg oil from said reservoir to lubricate thecompressor, mechanism for regulating the temperature of the compressor,and a thermostat subject to the temperature of the oil in the reservoirfor controlling the operation of said mechanism.

2. The combination with a rotary compressor, of a system for circulatingoil to lubricatethe'compressor, a system for circulating a coolingmedium throu h the compressor, and means subject to t e temperature ofthe oil for regulating the flow of cooling medium.

3. The combination with a rotary compressor, of a system for circulatingoil to lubricate the compressor and means for maintaining thetemperature of the compressor and thereby the fluid compressed by thecompressor at a tempe:ature above the vaporizing point of water andbelow the vaporizing point of the oil supplied to lubricate thecompressor.

4. The combination with a rotary compressor, of a reservoir containingoil, means a for supplying oil from said reservoir to lubricate thecompressor, mechanism for effecting the clrculation of a coollngll'qllld through the'compressor, a valve for controlling the flow ofcooling liquid, and a thermostat device subject to the temperature ofthe oil in said reservoir for operating said valve.

5. The combination with a rotary compressor, of a reservoir containingoil and into which flows fluid compressed by the compressor, means foreffecting the circulation of oil from the reservoirthrough the com-'pressor for lubricating said compressor, mechanism for effecting thecirculation of a cooling liquid through the compressor, a

valve for controlling the flow of cooling liquid, and a thermostatdevice subject to the temperature of the oil in .said reservoir foroperating said valve- In testimony. whereof I have hereunto set m hand.I

y CLYDE C. FARMER.

